Erosion wear performance of WC-10Co4Cr and Cr3C2-25NiCr coatings sprayed with high-velocity thermal spray processes

Thermally sprayed hardmetal coatings are widely used to protect components and surfaces against wear in various applications. Hard and wear resistant coatings increase the component lifetime and can generate significant savings promoting ecological manufacturing. This study focuses on the performance of tungsten carbide (WC-10Co4Cr) and chromium carbide (Cr3C2-25NiCr) based hardmetal coatings sprayed with gaseous and liquid fuelled high-velocity oxygen-fuel (HVOF) spray processes and a modern high-velocity air-fuel (HVAF) spray process. The coating characterisation revealed reduced carbide dissolution with decreasing process temperature and denser feedstock powder particles. Smaller carbide size in the Cr3C2-25NiCr material significantly reduced the carbide rebounding leading to higher carbide content in the sprayed coating and improved erosion wear resistance. Most significant improvements were observed in cavitation erosion for HVAF sprayed WC-10Co4Cr coatings (0.4 mu m/h) compared to the HVOF sprayed coatings (1.5-3.7 mu m/h). The cavitation erosion resistance of the HVAF sprayed coatings was almost at the level of the WC-10Co sintered bulk (0.2 mu m/h).